1. Field of the Invention
The present invention relates to a method for manufacturing a tube-type spray formed product and, in particular, to a method for manufacturing a tube-type spray formed product without using a core.
2. Description of the Background Art
In the conventional art for manufacturing a tube-type formed product using a spray forming method, the method of spraying droplets on a core has been used. Thus, there is an inconvenience in that the core and the tube-type formed product must be separated, in a case where only the tube-type formed product is desired to be used. In addition, there is a problem that a separate apparatus for manufacturing each tube-type formed product, that is, a particular core is required. This increases the unit cost of production and requires additional time and labor. Besides, there is a problem that it is not easy to release heat in a process of manufacturing a tube-type spray formed product to obtain a formed product with a uniform microstructure.
Currently, a seamless tube or a forged ring is manufactured by a continuous process where a billet manufactured by a casting or spray forming method is cut and internally machined and then tube-extruded or ring-forged. In this case, there is a disadvantage that additional time and labor is required for internally machining the billet and a loss of material occurs.
Hereinafter, the conventional art is described with reference to the accompanying drawings.
FIG. 1 is a schematic view illustrating a conventional spray forming method. As illustrated therein, this method is achieved in such a manner that molten metal is sprayed using a high pressure gas, and the droplets 2 of the spray move toward a plate while in an incompletely solidified state. The droplets are completely solidified only after they reach the plate, thereby forming a formed product 1, By using this method, a piece of metal material can be manufactured at a cooling rate of 103-105 K/sec. A bar-type or plate-type formed product can be directly manufactured according to the spray process and relative movement of a plate and an atomizer, so that the forming process can be shortened. Therefore, this manufacturing method can be applied to the quick solidification of commercial alloys, as well as the formation of metal material that are otherwise difficult to process, so that an interest is awakened in a new manufacturing method. Reference numerals 3, 4 and 5 in FIG. 1 illustrate a tundish, an atomizer and a molten metal, respectively.
FIG. 2 is a schematic view illustrating a method for manufacturing a conventional tube-type spray formed product. As illustrated therein, the product is manufactured by spraying droplets on a rotating member, shows as a core 6, by an atomizer. In this process, the core is disposable or semi-permanent. Currently, a stainless tube with a large diameter and a relatively small thickness is manufactured by this method. In addition, this method is applied to manufacturing in which the core material and formed product material are different from each other. However, as described above, there is an inconvenience in that the core 6 and the tube-type formed product 1 must be separated in order to produce only the tube-type formed product. Moreover, there is a problem that a separate member, that is, the core 6, for manufacturing each tube-type formed product 1 is additionally required, thereby increasing the unit cost of production and demanding additional time and labor in the manufacturing process.
FIG. 3 is a schematic view illustrating a conventional tube extrusion process, and FIG. 4 is a schematic view illustrating a conventional ring forging process. As illustrated therein, currently, a seamless tube or forged ring is manufactured by a continuous process where a billet manufactured by a casting or spray forming method is cut, internally machined, and then the tube is extruded or ring-forged. In this case, there is a disadvantage that a material loss occurs due to the machining of the interior of the billet, an also increasing the time taken for the process.
The present invention is directed to solve the above problems, and it is hence an object thereof to manufacture a tube-type spray formed product by directly using a conventional apparatus rather than using a separate apparatus. Accordingly, the invention reduces the additional costs incurred by the use of an additional apparatus and various forms of spray formed products can be obtained in the same manufacturing line.
In addition, it is another object of the present invention to provide a method for manufacturing a spray formed product capable of solving the above problems occurred due to the use of a core. That is, a spray formed product can be formed using the invention while reducing additional time and labor in a plan process and avoiding the inconvenience that the core and the formed product must be separated.
In addition, it is still another object of the present invention to obtain a tube-type spray formed product having a uniform microstructure by providing a process of manufacturing a tube-type spray formed product with excellent heat release characteristics.
In addition, it is yet still another object of the present invention to provide a method for manufacturing a tube-type spray formed product having a simple manufacturing process that does not have material loss, and which method is usable with a later applied tube extrusion or ring forging process.
In order to achieve the above objects, there is provided a method for manufacturing a tube-type spray formed product by spraying droplets from an atomizer that is installed at a position separated from the center of a rotating plate that is positioned so that droplets should not be sprayed on the center portion of the rotating plate. Accordingly, a tube-type spray formed product can be formed by using a conventional spray forming apparatus for manufacturing a bar-type formed product, without using a separate apparatus, for example, a core.
In accordance with a preferred embodiment of the present invention, the tube-type spray formed product is further subjected to a tube extrusion process or a ring forging process. By these two additional processes, the internal porosity of the formed product is reduced, the strength is increased, the structure is finished, and thereby it is possible to provide a tube or a ring with excellent mechanical properties.
In accordance with another embodiment of the present invention, a vibratory atomizer can be used, or a plurality of atomizers installed at different positions can be used in order for the diameter, thickness and forming speed of the tube-type spray formed product to meet the design objective.
The rotating plate in accordance with the present invention can move in the direction of the plate axis of rotation.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.